1. Field of the Invention
The present invention relates to a method of and an apparatus for removing a film layer on a glass plate for removing a film layer formed on one surface of a glass plate which is used as laminated glass or the like for a window of an automobile or as double glazing or the like for a window of a general building, as well as a glass-plate working apparatus having that apparatus.
2. Description of the Related Art
Laminated glass having the function of shielding heat rays, ultraviolet rays, visible rays, or the like is formed such that film layers for shielding heat rays, ultraviolet rays, visible rays, or the like are respectively formed on one surfaces of two glass plates by sputtering (metallic deposition) and are inwardly opposed to each other, and pressure, heat, and the like are applied to the two glass plates with a polyvinyl butyral sheet placed therebetween, thereby bonding the film layers and the polyvinyl butyral sheet. However, since the film layers and the polyvinyl butyral sheet are difficult to bond to each other, the state of their bonding is likely to become incomplete, and moisture, air, and the like can possibly enter peripheral portions of the laminated glass where the state of bonding is incomplete. Consequently, the polyvinyl butyral sheet becomes oxidized and undergoes color development and change. Accordingly, there is a need to remove the film layers at the peripheral portions so as to bond the glass plates and the polyvinyl butyral sheet which are easily bonded to each other. Meanwhile, double glazing having the function of shielding heat rays, ultraviolet rays, visible rays, or the like is formed such that film layers are respectively formed on one surfaces of two glass plates and are inwardly opposed to each other, and in order to obtain a hermetically sealed state between them, spacers are inserted between and bonded to the two glass plates at their peripheral portions by means of a pressure-sensitive adhesive elastic material (hereafter referred to as butyl rubber) formed of butyl and Thiokol (trade name). However, since the film layers and the butyl rubber are difficult to bond to each other, the state of their bonding is likely to become incomplete, and moisture and the like can possibly enter those portions where the state of bonding is incomplete, making it impossible to maintain the hermetically sealed state. Consequently, the heat insulating effect deteriorates appreciably, and water droplets and the like can occur on the film layers. Therefore, there is a need to remove the film layers at the peripheral portions so as to bond the glass plates and the butyl rubber which are easily bonded to each other.
In conjunction with the trend of automation of the motor vehicle traffic system in recent years, for example, automatic collection of a toll and the like is planned to be implemented in which an information recording medium such as a card is set on the windshield glass side in a vehicle, and the relevant information is automatically read from outside the vehicle by light rays for reading the information recorded on the card or the like. However, in the case where the film layers for shielding heat rays, ultraviolet rays, or the like are formed in the windshield glass of the vehicle, the transmittance of the reading light rays declines when the light rays are transmitted through the film layers, so that it is difficult to always reliably read the information recorded on the card or the like. Further, a stop lamp is provided on the rear window glass side inside a vehicle so as to rouse the attention of a following vehicle when a vehicle during traveling undergoes deceleration, stopping, or the like. However, in the case where the film layers (particularly dark-colored film layers) are formed in the rear window glass, when the light rays emitted from the stop lamp are transmitted through the film layers, the transmittance of the light rays declines. Hence, it is impossible to rouse sufficient attention of the following vehicle, and there is a risk of leading to a traffic accident such as a collision from behind. Accordingly, there is a need to enhance the transmittance of such light rays by removing (cutting off) the film layers in regions where the reading light rays and the light rays of the stop lamp are transmitted.
For the above reasons, regions and portions for which the film layers in the glass plates need to be removed are tending to increase.
Incidentally, in the case of removing a film layer for shielding heat rays, ultraviolet rays, visible rays, or the like, which is formed on one surface of a glass plate used for a vehicle, a general building, or the like for the purpose of maintenance of health, improvement of comfort, securing of privacy, and the like, the film layer in a specific region of the glass plate is conventionally removed while numerically controlling the movement of one removing head.
However, since the regions and portions for which the film layers in the glass plates need to be removed are tending to increase, as described above, a long time is required for removing the film layers in predetermined regions of the glass plates in a case where the single removing head is used. Hence, the improvement of productivity of these glass plates has been difficult, and has been a problem particularly in the working of window glass for motor vehicles for which high productivity is required.